Caseless pyrotechnic smoldering munition

ABSTRACT

Disclosed is a pyrotechnic smoldering munition for dissemination of the lacrimator O-chlorobenzal malononitrile (CS). The munition is made up of a pyrotechnic composition having a fire retardant coating. The pyrotechnic composition comprises the copolymerization product of an aromatic sulfur containing epoxy resin corresponding to the formula: WHERE N IS 1 TO 2 WITH MALEIC ANHYDRIDE AS BINDER FUEL. In addition to the binder fuel, the pyrotechnic composition comprises potassium chlorate as oxidizer together with the lacrimator (CS). The flame retardant coating, which contains ports for ignition of the pyrotechnic composition and exit of vaporized (CS), is a polyester resin produced by the condensation of dibromoneopentyl glycol and a mixture of phthalic and maleic anhydrides with an unsaturated monomer.

United States Patent 1 91 Drake et a].

[ 1 Jan. 23, 1973 [S41 CASELESS PYROTECHNIC SMOLDERING MUNITION [75] Inventors: Stevens S. Drake; George A. Lane,

both of Midland; Gerald R. Staudacher; Donald W. Girardin, both of Bay City, all of Mich.

[73] Assignee: The Dow Chemical Midland, Mich.

[22] Filed: Jan. 28,1971

[21] Appl. No.: 110,649

Company,

[52] US. Cl ..102/103, 102/90, lO2/D1G. 1, 149/7,149/8,149/19,149/83,149/94 [51] Int. Cl. ..C06d 7/00 [58] Field ofSearch ..l49/2, 19, 83,94,4,7, 11, 149/15, 8; 102/90, 103, DIG. l

[56] References Cited UNITED STATES PATENTS 2,643,184 6/1953 Cairns ..149/11 2,977,884 4/1961 Mahon et a1. ..102/103 3,108,433 10/1963 De Fries et a1. ....149/15 X 3,137,741 6/1964 Vondersmith et a1. ....149/ll X 3,269,313 8/1966 Willmann et a1. ....l02/90 X 3,454,436 7/1969 Bedell i ..l49/19 3,467,558 9/1969 Wcrnette ct 211.. ....l49/83 X 3,489,714 1/1970 Sayles ..102/103 X Primary ExaminerBenjamin R. Padgett Assistant Examiner-E. A. Miller Att0rneyGriswold & Burdick and William R. Norris [57] ABSTRACT Disclosed is a pyrotechnic smoldering munition for dissemination of the lacrimator O-chlorobenzal malononitrile (CS). The munition is made up of a pyrotechnic composition having a fire retardant coating. The pyrotechnic composition comprises the copolymerization product of an aromatic sulfur containing epoxy resin corresponding to the formula:

7 Claims, N0 Drawings C ASELESS PYROTECI-INIC SMOLDERING MUNITION BACKGROUND OF THE INVENTION In contrast to conventional munitions, caseless munitions based on a polymeric binder system introduce a new degree of freedom to the design of ordnance. Conventional pressed grains must be manufactured following a restricted geometry which accommodates the shortcomings of compaction technology. Pressed grains are limited to relatively simple structures of restricted diameter and mass, and design features such as undercuts and slanted center holes which are useful for controlling burning rates and rate of vapor releaseare forbidden. Munitions which are prepared by pourcasting a flowable composition and curing it to a coherent grain at elevated temperatures offer freedom of design not available in pressed munitions. Such freedom is especially desirable in munitions for the dissemination of lacrimators. In addition to the advantages inherent with a castable munition it would be desirable to prepare such a munition which smolders upon ignition to provide an even vaporization of the lacrimator without burning it.

There are also inherent advantages in a caseless munition due to the fact that no case remains after functioning. This is advantageous in riot control since spent cases have been used as missiles by rioters. In warfare, empty cases have been recovered by the enemy and employed to fabricate stores and weapons.

It is an object of the present invention to provide a caseless munition for the pyrotechnic dissemination of (CS).

An additional object is to provide such a munition which effectively disseminates (CS) without flaming.

Another object is to provide such a munition which is prepared by pour casting a flowable composition and heat curing to a coherent grain.

SUMMARY OF THE INVENTION The invention is a pyrotechnic smoldering munition for the dissemination of-the lacrimator (CS). The munition comprises a pyrotechnic composition for such dissemination encapsulated by a flame retardant coating to prevent flaming.

The pyrotechnic composition comprises from to percent of the copolymerization product of an aromatic sulfur containing epoxy resin corresponding to the formula:

o where n is l to 2 with maleic anhydride as binder fuel. The composition contains from 15 to percent of particulate potassium chlorate having particle size less than 30 mesh as oxidizer and the balance is (CS). As used herein, all percentages are on a weight basis.

The flame retardant coating, which contains one or more ports defining a passage from the surface of the pyrotechnic composition to the surface of the coating, is a brominated polyester resin prepared from the condensed product of dibromoneopentyl glycol and a mixture of phthalic and maleic anhydride with an unsaturated monomer.

DETAILED DESCRIPTION In a preferred embodiment the pyrotechnic composition contains from 23 to 25 percent binder fuel v'vitha maleic anhydride to epoxy weight ratio of about 0.65. The preferred oxidizer is particulate KClO- ranging in particle size from 30 to 400 mesh in an amount of from 28 to 30 percent of the composition. The preferred amount of (CS) is from 45 to 47 percent of the pyrotechnic composition.

In general the pyrotechnic composition is prepared by heating the epoxy/maleic anhydride combination to between and 80 C., usually 68-72, and blending in the oxidizer and (CS). The composition, which is flowable at the operating temperaturesi is poured into a mold of the desired shape and cured. The curing normally is carried out at a temperature of from 25 to 40 C. for a period of from 18 to 24 hours with postcuring for 2 hours at C. After curing, the composition has a tough, resilient consistency.

The fire retardant coating is prepared by condensing dibromoneopentyl glycol with a mixture of phthalic and maleic anhydrides with a comonomer. The molar ratio of dibromoneopentyl gylcolto anhydride is from l.l:l to 10:1. The'maleic/phthalic molar ratio may vary from percent maleic to 10 percent maleic, with 40 to 50 being preferred. The unsaturated monomer is added in an amount equal to from 20 to 60 percent preferably 35 to 40 percent of the glycol/anhydride combination. Examples of useful comonomers are styrene, monochlorostyrene, vinyltoluene and t-butylstyrene. At a temperature of from 20 to 35 C. the fire retardant composition is a flowable liquid which can be used to coat the pyrotechnic grain by conventional means such as by brushing, dipping, or spraying. The coating is gelled at ambient temperatures and cured at a temperature of from 25 to 70 C. One or more channels are cut through the coating to provide an entry for ignition and exit for vaporized (CS). The coating is normally applied in an. amount less than 10 percent of the uncoated munition.

It has been discovered that the addition of Sb 0 to the coating in an amount of from 2 to 15 percent provides a synergist for flame retardancy. Additionally, a 0.l% nitrocellulose coating maybe applied to the munition before the fire retardant coating. The nitrocellulose provides better wetting, and a smoother and more reliable polyester resin coating. The invention is further illustrated by the following examples:

EXAMPLEI To 70 gm. of warm epoxy resin in a stainless steel beaker is added 40 gm. of melted maleic anhydride. The mixture is stirred and a beaker mantle is used for heating. With the mixture beingheld at 65, 235 gm. of CS is added incrementally over a 30 minute period. The first 80 gm. dissolves; the remainder forms a dispersed paste. At 70 C., gm. KClO (dried 200 mesh)is added with mixing over a 10 minute period. The temperature is adjusted-to 68.72 C. to achieve a thin paste consistency for casting. The mixture is poured into a mold and the container vibrated' or tapped to eliminate air bubbles. The cast composition is cooled'at 20 C. for 15 to 30'minutes, cured'at 40 to 55 C. for 16 hours and postcured for 2 hours at 60 to 70 C.

The cured grains are removed from the molds and found to be coherent, tough, resilient articles. The grains are then coated with nitrocellulose lacquer, the nitrocellulose coating being from 0.05 to 0.20 percent on a weight basis of the uncoated grain. The nitrocellulose is applied from a percent solution in 75/25 methyl ethyl ketone/acetone to which 5 pph methanol has been added. Next, the nitrocellulose coated grain is coated with the brominated polyester resin. The polyester is the reaction product of stoichiometric amounts of dibromoneopentyl glycol and a 50/50 mixture of phthalic and maleic anhydrides. The polyester is dissolved in styrene to form a 60/40 solution and catalyzed for use with 1.0 to 1.25 percent benzoyl peroxide and 0.20 to 0.25 percent dimethylaniline with Sb 0 at 6 phr being added as a synergist for flame retardancy.

Five cylindrical grains of 75 gm. each were prepared and placed under accelerated surveillance (90 C. for 16 hours). Table l indicates the amount of coating used white smoke EXAMPLE ll:

Several grains were prepared as before with brominated polyester, BrPE (50/50 maleic/phthalic anhydrides), in monochlorostyrene, MCS, at a ratio of 60/40 BrPe/MCS. The catalyst of benzoyl peroxide/dimethylaniline was adjusted for a gel time of 20 minutes, and Sb 0 used at 6 phr.

Table II sets out surveillance and performance data for several grains prepared in this manner.

TABLE ll Surveil- Coating lance Duration NC% Br Comments Cyclic" 4 cycles 0.14 8.5 BT 43 sec., y 34%,

Cyclic 4 cycles 0.l6 7.) BT 42 sec., flaming at [0 see. as piece broke off Cyclic cycles 0.12 7.6 No apparent degradation,

no blisters Cyclic l5 cycles 0!? 8.6 No apparent degradation.

' no blisters High 3 days 0.1 l 5.) Run as control, BT 4| Temp. sec., y 37%. E 68% High 13 days 0.16 42 BT 43 sec. %Y/%E Temp. 34/72 High Temp. 31 days 0.18 7.8 Good shape, no blisters High Temp. 31 days 0.47 6.2 Good shape. no blisters High Temp. 3l days 0.13 6.9 Good shape, no blisters High Temp. 31 days O.l3 6.2 Good shape, no blisters BT functioning time %Y grams of generated CS aerosol per I00 g. of total pyrotechnic composition.

%E grams of generated CS aerosol per g. of CS in the pyrotechnic composition a. One cycle 7 1 C for at least 4 hrs. 54C for at least 4 hrs.

-CH2CH--CH2 wherein n is a number from 1 to 2,

ii. from 15 to 35 percent of particulate potassium chlorate as oxidizer, and iii. the balance a lacrimator of O-chlorobenzal malononitrile, and:

b. a uniform flame retardant coating covering the surface of said body to form an exterior wall thereof, said coating comprising the condensation product of dibromoneopentyl glycol and a mixture of phthalic and maleic anhydrides with an unsaturated monomer, said munition being further characterized by the coating encapsulating the pyrotechnic composition with the exception of one or more ports in the coating which define a passage from the surface of the pyrotechnic composition to the surface of the coating.

2. The munition of claim 1 wherein the potassium chlorate ranges in particle size from 30 to 400 mesh on the US. Standard Sieve Series.

3. The munition of claim 1 wherein the ratio of dibromoneopentyl glycol to anhydride is from 1.111 to 1.0:].

4. The munition of claim 1 wherein the unsaturated monomer is employed in an amount of from 20 to 60 percent of the glycol/anhydride combination.

5. The munition of claim 1 wherein the unsaturated monomer is styrene, monochlorostyrene, vinyltoluene or t-butylstyrene.

6. The munition of claim 1 wherein the composition of said film contains in addition from 2 to 15 percent Sb203 7. The munition of claim 1 including a second coating covering the surface of said body said second coating being disposed between the body and said flame retardant coating, said second coating comprising nitrocellulose in an amount of about 0.1 per cent by weight of said body. 

2. The munition of claim 1 wherein the potassium chlorate ranges in particle size from 30 to 400 mesh on the U.S. Standard Sieve Series.
 3. The munition of claim 1 wherein the ratio of dibromoneopentyl glycol to anhydride is from 1.1:1 to 1.0:1.
 4. The munition of claim 1 wherein the unsaturated monomer is employed in an amount of from 20 to 60 percent of the glycol/anhydride combination.
 5. The munition of claim 1 wherein the unsaturated monomer is styrene, monochlorostyrene, vinyltoluene or t-butylstyrene.
 6. The munition of claim 1 wherein the composition of said film contains in addition from 2 to 15 percent Sb203.
 7. The munition of claim 1 including a second coating covering the surface of said body said second coating being disposed between the body and said flame retardant coating, said second coating comprising nitrocellulose in an amount of about 0.1 per cent by weight of said body. 